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Indoor, soil based activities.
- Thread starter LndRcLvr
- Start date
@GMT I'm not sure my friend. But I have a light meter on my phone and with the light at its highest position and measured at the surface of the leaves it's giving the leaves over 430 ppfd in centre 380 at the sides - when it's was half height it was well over 1000 I can't remember but it was probably over 1500 ppfd
2nd Feb 08:00
Outside temp 9c
Room. MAX 29.3 66.3%rh. MIN 21.8 44%rh
Plants. Progressive growth, no issues
Actions lightly hosed room down again + surface of soil adjusted extraction upwards like 2%
Notes. Noticed a bug flying around last night probably gnats or fruit flies from compost. Ordered Fly paper. Seems when I reduce ventilation temps go up from light heat so currently unable to increase humidity unless I use water spray and wet towels in room. Extra towel and regular soaking seem to be helping keep it between 45 and 65rh. Plants seem happy
Outside temp 9c
Room. MAX 29.3 66.3%rh. MIN 21.8 44%rh
Plants. Progressive growth, no issues
Actions lightly hosed room down again + surface of soil adjusted extraction upwards like 2%
Notes. Noticed a bug flying around last night probably gnats or fruit flies from compost. Ordered Fly paper. Seems when I reduce ventilation temps go up from light heat so currently unable to increase humidity unless I use water spray and wet towels in room. Extra towel and regular soaking seem to be helping keep it between 45 and 65rh. Plants seem happy
Everything sounds so weird to me I'm starting to question if I actually know anything. I'm also running 500 ISH watts here, (300, 150, 5) ok, 455. The inside of my window looks like the inside of a goldfish bowl every morning.
Your area is twice mine and from what you say, have more plant power per sqf than i do.
I really feel like I should give up offering any suggestions at this point, I think you're growing in the twilight zone.
Your area is twice mine and from what you say, have more plant power per sqf than i do.
I really feel like I should give up offering any suggestions at this point, I think you're growing in the twilight zone.
Yeah that makes it 500w lol. The 1000w is the manufacturer's opinion on it's equivalent to hps style lighting. It's usable plant energy equivalent supposedly. But in reality it's just a marketing gimmick. If it uses 500w, it's a 500w light. Now depending on the spectrum, that does mean you can use less watts. For instance my 300w led is equivalent to my 400w hps providing I adjust my grow style and nutrients to match led requirements. I am sure led tech. has come a long way since I started with them. And I'm not for a second saying it can't be so. But for them to now be putting out twice the usable light they were 3 years ago, esp since you say it also puts out a lot of heat, it just doesn't seem feasible to me. I'm trying to think who to call in on this. But I haven't seen f-e for ages. Kopite isn't around anymore. Haven't even seen dankfrank for a while. I'm sure @Ca++ could chip in, or @Creeperpark . But like I said, I really think this is where I have to throw my hat away.
Ca++
Well-known member
Yup. 500 is 500
The "watt" rating on a light, tells us how much electricity is being used. It is not a measure of how bright the light is. The lights power use, just gives us a rough idea.
We can safely say a 400w MH, is brighter than a 250w MH. Both are MH, so this expectation is reasonable.
If we compare a 400w MH to a 250w LED, the answer isn't so simple. Both could easily light up the same. Different power used, but just as bright.
It's all about how many photons we get from the light, for the electric it uses. We talk about this, in terms of how much light, per watt. It's not uncommon to see a MH rated around 100 lumens per watt, giving us 40,000 lumens
This next pic is a 4000K 250w LED, making 39300lm
Same light, but different tech making it.
All lights are not equal. It got confusing. Manufacturers were told to make comparisons to the old incandescent lamps, these replaced.
So it's also using 9.5w of electric. To make 800 lumens this time. And importantly we see the equivalent figure. It replaces a 60.
This is as bright as a 100, but uses just 10.5W, which is impressive. The best in class can replace a 100 using just 9.5W. So we are looking at 150Lm/W which is 50% better than the MH. If we move along to the top tech we buy our plants, the common LM301 produces 220Lm/W which is double the MH. So while the 400 made 40,000 the 250w LED could do over 50,000 using the LM301.
Again, we had LED entering a new market. This time where everyone once used HPS and also talked about power use. The 400, the 600. Just power used.
Asking how many watts someone had, of what type of light, used to tell us enough. Not with LED though, where one could be twice as good as another.
The sellers were quick to see we needed equivalents. Things like saying you have a 500W LED, that will work like a 1000W HPS. The lack of standardisation soon had sellers spinning a load of lies though. These statements were not enframed by law, so they could just pretend.
Lm/W is alright for talking about older lighting, but now things have moved on, and so have we. Light is now measured in plant terms, not human ones, and so it's no longer lumens. Now we are measuring in umol/W not Lm/W, but it is still brightness. To look at this 500 vs a 1000, I will need to move to light in umol.
A 1000 is typically 1.7umol/W, giving it 1700umol in total. If we want that from just 500w, we need more than that 1.7umol/W. We need 3.4umol/W, and we should be sceptical of any such claim. Good brandless LEDs might make 2-2.4umol/w. The 301 based lights maybe 2.8umol/w. If you want 3umol/w then adding high efficiency reds can get you there, but the light is turning pink. The 3.4umol claim is rarely made. It would be reds and blues, with a couple of whites. Things do move fast though. This post has taken so long, there have probably been advances.
500w though. That's what is is, and how it should be thought of. Especially when you need to look at other peoples grows for comparison.
@Ca++ wow! Thank you for taking the time to explain this in such detail it has given me a lot More clarity on the situation. It leads me to ask two questions ( you can keep the answers short if you want to! )Yup. 500 is 500
The "watt" rating on a light, tells us how much electricity is being used. It is not a measure of how bright the light is. The lights power use, just gives us a rough idea.
We can safely say a 400w MH, is brighter than a 250w MH. Both are MH, so this expectation is reasonable.
If we compare a 400w MH to a 250w LED, the answer isn't so simple. Both could easily light up the same. Different power used, but just as bright.
It's all about how many photons we get from the light, for the electric it uses. We talk about this, in terms of how much light, per watt. It's not uncommon to see a MH rated around 100 lumens per watt, giving us 40,000 lumens
This next pic is a 4000K 250w LED, making 39300lm
Same light, but different tech making it.
All lights are not equal. It got confusing. Manufacturers were told to make comparisons to the old incandescent lamps, these replaced.
So it's also using 9.5w of electric. To make 800 lumens this time. And importantly we see the equivalent figure. It replaces a 60.
This is as bright as a 100, but uses just 10.5W, which is impressive. The best in class can replace a 100 using just 9.5W. So we are looking at 150Lm/W which is 50% better than the MH. If we move along to the top tech we buy our plants, the common LM301 produces 220Lm/W which is double the MH. So while the 400 made 40,000 the 250w LED could do over 50,000 using the LM301.
Again, we had LED entering a new market. This time where everyone once used HPS and also talked about power use. The 400, the 600. Just power used.
Asking how many watts someone had, of what type of light, used to tell us enough. Not with LED though, where one could be twice as good as another.
The sellers were quick to see we needed equivalents. Things like saying you have a 500W LED, that will work like a 1000W HPS. The lack of standardisation soon had sellers spinning a load of lies though. These statements were not enframed by law, so they could just pretend.
Lm/W is alright for talking about older lighting, but now things have moved on, and so have we. Light is now measured in plant terms, not human ones, and so it's no longer lumens. Now we are measuring in umol/W not Lm/W, but it is still brightness. To look at this 500 vs a 1000, I will need to move to light in umol.
A 1000 is typically 1.7umol/W, giving it 1700umol in total. If we want that from just 500w, we need more than that 1.7umol/W. We need 3.4umol/W, and we should be sceptical of any such claim. Good brandless LEDs might make 2-2.4umol/w. The 301 based lights maybe 2.8umol/w. If you want 3umol/w then adding high efficiency reds can get you there, but the light is turning pink. The 3.4umol claim is rarely made. It would be reds and blues, with a couple of whites. Things do move fast though. This post has taken so long, there have probably been advances.
500w though. That's what is is, and how it should be thought of. Especially when you need to look at other peoples grows for comparison.
1: is it possible for me (how do I?) calculate the actual strength of my light in umols/w using my fairly accurate phone app 'photone' or perhaps using a number of apps and using an average reading.?
Thank you again I appreciate your input
3rd Feb 22:00
Outside temp 11c
Room: Max 29c 71% rh Min 27c 47%rh
Plants. Active growth, gaining size quickly. some patchy colouring on some plants
Actions. Wet room down. Increased extract fan slightly. Also wetting area outside room
Notes. Outside air temp up so I suspect it's pushing up temps a bit. Trying slightly higher extract to see what happens. When lights are off heater timed on and temps holding 17c - 21c soon will add timer onto extract fan also to see what effect it has. have noticed humidity goes up significantly when lights are off
Outside temp 11c
Room: Max 29c 71% rh Min 27c 47%rh
Plants. Active growth, gaining size quickly. some patchy colouring on some plants
Actions. Wet room down. Increased extract fan slightly. Also wetting area outside room
Notes. Outside air temp up so I suspect it's pushing up temps a bit. Trying slightly higher extract to see what happens. When lights are off heater timed on and temps holding 17c - 21c soon will add timer onto extract fan also to see what effect it has. have noticed humidity goes up significantly when lights are off
Last edited:
4th Feb 22.00
Room max 29c 73% min 19c 42 %
Plants. Growing fast patchy lighter area looking bleached.
Actions wet towels and sprayed room. Removed weed seedlings, squashed a few bugs.
Notes. Gnats / flies starting to become more common, numerous weed seedlings germinating some spiders taken up residence on light, spinning webs. Fly paper en route
Room max 29c 73% min 19c 42 %
Plants. Growing fast patchy lighter area looking bleached.
Actions wet towels and sprayed room. Removed weed seedlings, squashed a few bugs.
Notes. Gnats / flies starting to become more common, numerous weed seedlings germinating some spiders taken up residence on light, spinning webs. Fly paper en route
Ca++
Well-known member
The measurement at the canopy is the important thing, but the measurements accuracy is debatable, when it's measured with an app on an unknown phone.@Ca++ wow! Thank you for taking the time to explain this in such detail it has given me a lot More clarity on the situation. It leads me to ask two questions ( you can keep the answers short if you want to! )
1: is it possible for me (how do I?) calculate the actual strength of my light in umols/w using my fairly accurate phone app 'photone' or perhaps using a number of apps and using an average reading.?
2: Have I got enough light for the flowering footprint the light states which is 1.5m x 1.5m?EDIT - I've realised this depends on the answer to the first question so you don't need to answer that one
Thank you again I appreciate your input
If you divide your 2.25 meters into a grid, maybe 6x6, then you can see the average umol/m reading over the entire space. By measuring each square in the grid, adding all the results, and dividing by the total number of squares (6x6=36).
With the average known, trying to light 2.25sqm, you can see what a meter might look like. It would be 2.25 times stronger. Now we have a more solid figure to work with, as a meter is what the light meter thought you had anyway. All of this came from the light, with perhaps a 20% loss. So to talk about light emitted, we need to add 25%.
Lets do that with some numbers.
Say your 6x6 grid all measures 500umol/w. You add all 36 squares up, to get the total of 18000, which needs dividing by 36, to see the average reading. Which we know was 500umol/m
This was over 2.25m, so to see what our light can do focused on one meter, we have 500x2.25= 1125umol/m.
If was not strictly necessary to get it over a meter, but is conventional, and the type of maths we revolve around.
All these 1125umol came from the light, but perhaps 20% were lost, so add 25% and we have 1406umol total emitted. This we believe was made with 500w. So 1406/500=2.8125umol/w
A lot was lost in translation there. From the accuracy of the light meter, to the accuracy of a 20% loss, through to the belief it uses 500w. However, with no other way to rate your light, the number is interesting. Though ultimately, what your phone said was the import bit for the plants. They really don't care about our power bills, or our lighting efficiency. They won't even read my post
I'm going to attempt to practically apply this theory, to at least get a bit closer to the truth.The measurement at the canopy is the important thing, but the measurements accuracy is debatable, when it's measured with an app on an unknown phone.
If you divide your 2.25 meters into a grid, maybe 6x6, then you can see the average umol/m reading over the entire space. By measuring each square in the grid, adding all the results, and dividing by the total number of squares (6x6=36).
With the average known, trying to light 2.25sqm, you can see what a meter might look like. It would be 2.25 times stronger. Now we have a more solid figure to work with, as a meter is what the light meter thought you had anyway. All of this came from the light, with perhaps a 20% loss. So to talk about light emitted, we need to add 25%.
Lets do that with some numbers.
Say your 6x6 grid all measures 500umol/w. You add all 36 squares up, to get the total of 18000, which needs dividing by 36, to see the average reading. Which we know was 500umol/m
This was over 2.25m, so to see what our light can do focused on one meter, we have 500x2.25= 1125umol/m.
If was not strictly necessary to get it over a meter, but is conventional, and the type of maths we revolve around.
All these 1125umol came from the light, but perhaps 20% were lost, so add 25% and we have 1406umol total emitted. This we believe was made with 500w. So 1406/500=2.8125umol/w
A lot was lost in translation there. From the accuracy of the light meter, to the accuracy of a 20% loss, through to the belief it uses 500w. However, with no other way to rate your light, the number is interesting. Though ultimately, what your phone said was the import bit for the plants. They really don't care about our power bills, or our lighting efficiency. They won't even read my post
I have two questions.
Do I need to measure the light in straight umols?
You mention umols/m a lot is that a different reading?
Also
Do I need to set the light to a specific height from the canopy to take the readings?
I sort of understand you are multiplying by 2.25 to show the intensity of light, if the same amount of light was focused on just one sq meter rather than 2.25 sq
I'm slowly get my head round this stuff but I find it fairly complicated
Thank you thank you thank you!
@Ca++
I've gone and done it. Tried to be as methodical as I can with the measurements.
The space I have measured is 1.33m (max width) by 1.33m to keep it simple and divided it into 25 squares. The light is roughly mounted in the centre probably off by a cm or 2 ( I have to say fuck it at some point)
So following your calculations:
Total of squares divided by 25
8067 / 25 = 322.68
1.33 * 1.33 = 1.76sq m surface area
322.68 * 1.77 = 571.14
571.14* 25% = 714
714 / 500 = 1.42umols /w
That seems disappointingly low.
So a) I've completely messed up the measurements.
B) my phone app is not accurate
C) I have been ripped off
Website says
- High PPF of 1670 µmol/s and Photon Efficacy 2.7 µmol/J.
Now I'm not trying to persuade myself my light is better than it is but what I have now noticed is that the height I have the light hung is twice the height recommended. but that's to keep the ppfd down around 400
From the website:
Best hanging heights for skyline
Vegetative stage: 24 to 30 inches (60 to 76cm)
Flowering stage: 14 to 20 inches (35.5 to 50.8cm)
Im going to adjust the height and take a quick measurement
Last edited:
Measured at 800mm from canopy
There is a big hotspot in the middle at this height
So following your calculations:
Total of squares divided by 25
11495/ 25 = 459.8
1.33 * 1.33 = 1.76sq m surface area
459.8 * 1.77 = 813.8
813.8* 25% = 1017.25
1017/500 = 2.03 umols /w
this seems more reasonable but as mentioned there is a big hotspot in middle which is not ideal.
I have raised the light back up, but lower than before so the middle reads 570 and inner circle around that it's about 420 - 470 now. Edges coming in low to mid 300s
I'm going to take a chance with this
I need to go to bed. Goodnight.
There is a big hotspot in the middle at this height
So following your calculations:
Total of squares divided by 25
11495/ 25 = 459.8
1.33 * 1.33 = 1.76sq m surface area
459.8 * 1.77 = 813.8
813.8* 25% = 1017.25
1017/500 = 2.03 umols /w
this seems more reasonable but as mentioned there is a big hotspot in middle which is not ideal.
I have raised the light back up, but lower than before so the middle reads 570 and inner circle around that it's about 420 - 470 now. Edges coming in low to mid 300s
I'm going to take a chance with this
I need to go to bed. Goodnight.
Ca++
Well-known member
Is your tent 1.33 or 1.5?
If you have only measured 1.33 of 1.5, then you missed a bit. Half a meter. Though a weakly lit half meter.
We talk about plant illumination, in terms of how much useful photonic energy, falls on a meter, in a second. When your phone says 910umol, it doesn't mean 910umol fell upon the light sensor. It wasn't even 1umol that fell upon the light sensor. But it knows how small it is, so can work out what a meter of that would add up to. PPFD is a metric thing, and a meter a standard metric unit. So no matter the size of your sample, we all meet on common ground, talking about light per meter. Unless you are living in the dark ages of foot candles. Where again, it's light falling on a specific area, in a specific time.
You took 25 reads of what a meter2 would look like. 25 different numbers, to find the average illumination of your meter2. Except you don't have a meter2. If all your light was in a meter, it would be brighter. As you have watered it down somewhat, spreading is over 1.76-2.25sqm. So we are not directly measuring your meter to see what light you have put into it. We are measuring a bigger space, than maths takes us to per meter numbers.
I seem to be better at doing it, than explaining it.
Your numbers do seem low, right from the initial reads. It's not a maths error, I think it's the phone app.
Do you have a power metering plug adaptor?
I think I pay about £7 from Ali. Don't hold me to that though. It might cost more. They are a good tool though. Allowing you to see what power is really being used, which is great in day to day life. I'm forever turning my lights down to work on the plants, then back up to the same level as before. It's easy to be consistent with these. It's more use, than just seeing how powerful your new light is.
If you have only measured 1.33 of 1.5, then you missed a bit. Half a meter. Though a weakly lit half meter.
We talk about plant illumination, in terms of how much useful photonic energy, falls on a meter, in a second. When your phone says 910umol, it doesn't mean 910umol fell upon the light sensor. It wasn't even 1umol that fell upon the light sensor. But it knows how small it is, so can work out what a meter of that would add up to. PPFD is a metric thing, and a meter a standard metric unit. So no matter the size of your sample, we all meet on common ground, talking about light per meter. Unless you are living in the dark ages of foot candles. Where again, it's light falling on a specific area, in a specific time.
You took 25 reads of what a meter2 would look like. 25 different numbers, to find the average illumination of your meter2. Except you don't have a meter2. If all your light was in a meter, it would be brighter. As you have watered it down somewhat, spreading is over 1.76-2.25sqm. So we are not directly measuring your meter to see what light you have put into it. We are measuring a bigger space, than maths takes us to per meter numbers.
I seem to be better at doing it, than explaining it.
Your numbers do seem low, right from the initial reads. It's not a maths error, I think it's the phone app.
Do you have a power metering plug adaptor?
I think I pay about £7 from Ali. Don't hold me to that though. It might cost more. They are a good tool though. Allowing you to see what power is really being used, which is great in day to day life. I'm forever turning my lights down to work on the plants, then back up to the same level as before. It's easy to be consistent with these. It's more use, than just seeing how powerful your new light is.
